1. Field of the Invention
The present invention relates to a golf club shaft.
2. Description of the Related Art
A so-called carbon shaft has been known as a golf club shaft. A sheet winding method has been known as a method for manufacturing the carbon shaft. In the sheet winding method, a laminated structure is obtained by winding a prepreg (prepreg sheet) around a mandrel. In the sheet winding method, the type of a sheet, the disposal of the sheet, and the orientation of a fiber can be selected. Therefore, a high degree of freedom in design is obtained.
The prepreg includes a resin and a fiber. Many types of prepregs exist. A plurality of prepregs having different resin contents has been known. In the present application, the prepreg is also referred to as a prepreg sheet or a sheet.
In a tubular body described in Japanese Patent Application Publication No. 3235964 (U.S. Pat. No. 6,106,413, U.S. Pat. No. 6,524,195), a prepreg having a synthetic resin impregnating amount of 10% by weight or greater and less than 25% by weight is used as a skew fiber body layer and an axial fiber body layer. In this invention, a thin layer having a great synthetic resin impregnating amount is formed between the skew fiber body layer and the axial fiber body layer.
Japanese Patent Application Laid-Open No. 11-206934 discloses a shaft including an axially elongated fiber layer and an oblique fiber layer. At least one of the axially elongated fiber layer and the oblique fiber layer includes a prepreg having a low resin impregnating amount of 10 to 24% by weight. A layer including a prepreg having a high resin impregnating amount of 10% by weight or higher than that of the prepreg is formed on the inner and outer layer sides of a layer formed by the prepreg.